[templates] Update head

To allow changing the custom GIN header content via the
gogs custom templates, the corresponding code is moved
to its own template file.

Should enable easy updates for in-house-gin deployments.

templates/base/head.tmpl

@@ -110,8 +110,7 @@
 									</div>
 									</div>*/}}
 
-								<a class="item" href="/G-Node/info/wiki" rel="noreferrer"><i class="octicon octicon-question"></i>{{.i18n.Tr "help"}}</a>
-								<a class="item" href="/G-Node/Info/wiki/News">News</a>
+								{{template "base/head_gin" $}}
 								{{if .IsLogged}}
 									<div class="right menu">
 										<div class="ui dropdown head link jump item poping up" data-content="{{.i18n.Tr "create_new"}}" data-variation="tiny inverted">

templates/base/head_gin.tmpl

@@ -0,0 +1,2 @@
+<a class="item" href="/G-Node/info/wiki" rel="noreferrer"><i class="octicon octicon-question"></i>{{.i18n.Tr "help"}}</a>
+<a class="item" href="/G-Node/Info/wiki/News">News</a>